A team of researchers has found that mothers of preterm babies have highly individual breast milk microbiomes and that even short courses of antibiotics have prolonged effects on the diversity and abundance of microbes in their milk.
The study led by researchers from the University of Toronto and The Hospital for Sick Children was once published in the publication Cell Host and Microbe.
The study is the largest to date of breast milk microbiota in mothers of preterm infants, and it’s the first to show that antibiotic class, timing and duration of exposure have specific effects on the commonest microbes in breast milk — many of which have the potential to influence growth and immunity to disease in new-borns.
“It came as slightly a shock to us that even sooner or later of antibiotics was once associated with profound changes in the microbiota of breast milk,” says Deborah O’Connor, who is a professor and chair of nutritional sciences at U of T and a senior associate scientist at SickKids. “I think the take-home is that while antibiotics are incessantly an fundamental remedy for mothers of preterm infants, clinicians and patients must be judicious in their use.”
Most antibiotic stewardship programs in neonatal intensive care focus on limiting use in newborns themselves. The current study adds to growing evidence that these programs must include a focus on mothers as polite, says O’Connor, principal investigator on the study who could also be a scientist in the Joannah & Brian Lawson Centre for Child Nutrition.
The researchers looked at 490 breast milk samples from 86 mothers whose infants were born preterm, all over the first eight weeks after delivery. They found that the mothers’ body mass index and mode of delivery influenced the breast milk microbiota, consistent with some other studies.
But the effects of antibiotics were the most pronounced, and in some cases, they lasted for weeks. Lots of the antibiotic-induced changes affected key microbes known to play a role in fostering disease, or in intestine health and metabolic processes that promote babies’ growth and development.
“Overall we saw a decrease in metabolic pathways, and increase in more pathogenic pathways in bacteria over the years,” says Michelle Asbury, a doctoral student in O’Connor’s lab and lead creator on the paper. “Of specific concern was once an organization between antibiotics and a member of the Proteobacteria phylum called Pseudomonas. When elevated, Proteobacteria in a preterm infant’s intestine can precede necrotizing enterocolitis.”
Approximately seven per cent of babies born preterm develop necrotizing enterocolitis, a continuously fatal condition in which a part of the bowel dies. A class of antibiotics called cephalosporins also had a big effect on the overall diversity of breast milk microbiota.
Asbury says it is too early to realize what the findings intent for preterm infant health and outcomes. She and her colleagues will dive into those questions over the next year, as they compare their findings with stool samples from the preterm infants involved in the study. This must reveal if changes in the mothers’ milk microbiomes are in reality seeding the infants’ guts to elevate health or increase disease risk.
Meantime, she says it’s important that mothers with preterm infants continue to take antibiotics for some cases of mastitis, blood infections and early rupture of membranes. Kind of 60 per cent of women in the current study took antibiotics — highlighting both the huge need for these drugs and the possibility of some overuse.
Sharon Unger is a co-author on the study and a professor of paediatrics at U of T, in addition to a scientist and neonatologist at Sinai Health and SickKids. She says that some great benefits of breast feeding far outweigh the risk that antibiotics can disrupt the breast milk microbiome, and that mothers must without question continue to supply their own milk when imaginable.
“But I think we will be able to look to narrow the spectrum of antibiotics we use and to shorten the duration when imaginable,” Unger says. She adds that advances in technology may allow for quicker diagnoses of infection and better antibiotic stewardship at some point.
As for the unexpectedly moving field of microbiome research, Unger says it holds great promise for preterm infants. “Clearly the microbiome is important for their metabolism, growth and immunity. But emerging evidence on the gut-brain axis and its potential to further fortify neurodevelopment for these babies over the longer term warps my brain.”
(This story has been published from a wire agency feed without modifications to the text. Only the headline has been changed.)
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